Arrangement for radio circuits



March 7, 1933. w. BUSCHB ECK ARRANGEMENT FOR RADIO CIRCUITS Filed Dec. 28, 1928 Qvwentoz WERNER BUSCHBECK 35 his QM QWW QM%/ i NITED STATES Patented Mar. 7, 1933 'PATENT- OFFICE mama BUSCI-IBECK, or BERLIN, GERMANY, ,ASSiGNOR TO TELEFUNKEN GEIsELL- SGHAFT rim DRAHTLOSE TELEGRAIHIE M. B. or BERLIN, GERMANY, A Conro- RATION OF GERMANY ARRANGEMENT FOB RADIO CIRCUITS Application filed December 28, 1928, Serial No. 328,876, and in Germany December 81, 1927. v

One of the difliculties encountered in the design of radio circuits is the problem of suppressing radio frequency currents from certain circuits of the system. Various means have been devised but in each instance the result has been either imperfect or other disadvantages have been introduced which more than over-balance the advantages of the system.

For instance citing a familiar example, in transmitter apparatus according to the usual former practice a plate or a grid choke-coil is frequently employed for the purpose of separating the direct current path from the radio frequency current.

When a large choke coil is used, and in order to be effective choke coils must be of comparatively large size, the choke coil will start to oscillate at itsnatural period especially in the case of short leads, which action is attended often with the inconvenience that the choke coil constituting a selfoscillatory system upon being set into oscillation will result in large losses in the sys tem and under certain circumstances even ceasing of the waves owing to undue energy absorption will result.

The main purpose of this invention isto overcome all of the above mentioned difiiculties. 7

Another object of this invention is to insure stopping of radio frequency currents wherever this action is desired.

Still another object of the invention is the obtaining of a perfect choke.

Another object of the invention is to limit the length of wire required for the choke coil and thus avoid all the difficulties presented by the great length of wire customarilv used.

Still other objects of the invention will become apparent when reading the following detailed description in connection with the drawing in which:

Figure 1 illustratesdiagrammatically the that my invention may be applied in any type of circuit where, for any reason whatever, a choking action is desired, and that I do not intend the two illustrations to be in any way or form limitations on the dev1ce.

In thedrawing, Figure 1, a vacuum tube oscillator or transmitter 1 having the usual anode 12, grid electrode 11 and cathode 10 is shown having the usual power supply connections 7 and 8. The filament 10 is energized as usual by the'source 9. The grid cathode circuit comprises the parallel arrangement of inductance 5 and capacity 6. The plate filament circuit consists of the blocking condenser. 3, and the oscillatory cir- 7 cuit 2 consisting of the parallel arrangement of inductance L and capacity C. T

0011A: is the choke coil as employed'for purposes of this invention. This coil may be constructed of a comparatively few number ofturns. According. to the invention .coil 4: is coupled with coil L by coupling M so that a counterelectromotive force is produced. The coupling, of course, must be variable so that the counter electromotive 8 force obtained may be adjusted to be approximately equal to the potential obtained with the usual connection of the choke coil with the oscillation circuit.

a If choke coil 4 is coupled to L variable alternating current potential from L may be induced in 4 in proper phase and amplitude to compensate the alternating current impressed conductively on 4.

It will beiunderstood that a similar proinvention as applied to a transmitter Icir- 69 :upon said first named means alternating curcedur-e is possible for the purpose of increasing the choke action of the choke coil connected in the grid circuit of a vacuum tube.

Figure 2 shows a portion of a receiving circuit incorporating my invention.

Tube 20 is a usual triode having input circuit 26, fed with signal energy from 27, filament supply 21 and plate supply as shown in the illustration by Ev-supply. The output of tube 20'is coupled to the input of another tube 25 in cascade arrangement through transformer 24.

, As is usual in such circuits it is desirable to prevent the high frequency energy from entering the supply circuit, hence, coil is usually placed as shown by 4.

According to this invention the coil 4: is

coupled with coil 23 through coupling M whereby any high frequency energy can be totally or partially counterbalanced as discussed in more detail in connection with Figure 1.

It will thus be seen that all that need be done to apply my invention to any set of conditions is to calculate the amount of coupling M which is needed to counteract the energy in the choke coil.

Having thus described my invention, what I desire to protect by Letters Patent is:

I. In an electrical system, means for preventing high frequency energy from passing into any desired branch thereof, comprising a choke coil connected in series with the desired branch and means for coupling said choke coil with another coil connected to any other part of the system passed by the high frequency energy and means controlled thereby for setting up in said choke coil an electromotive force of such a value that the electro motive force caused by any alternating current energy in said choke coil is neutralized.

a choke trodes, means for impressing alternating current potentials on said input electrodes whereby said potentials may be repeated in said tube and appear on said output electrodes, a compound circuit connected between said output electrodes, said compound circuit including an alternating current branch and a direct current branch, and means for preventing alternating current potentials in said alternating current branch from afiecting said direct current branch including an inductance in each of said branches, said inductances being electromagnetically coupled.

WVERNER BUSOHBECK.

2. in a space discharge device circuit having an alternating current input circuit and an alternating current output circuit, means for preventing direct current from flowing in saidoutput circuit, a source of direct current anode potential and a choke coil in series shunted across said output circuit and means including a portion of said output circuit for impressing an electromotive force upon said coil.

3. In a spacedischarge device circuit having alternating current input and output circuits, a source of anode potential shunted across said output circuit, inductive means in serieswith said source for offering a high resistance path to alternating current energy from said space discharge device circuit and means in said output circuit for impressing rent energy equal and opposite to the alternating current energy desired to be eliminated from said source.

4. Inisignal relaying means, a thermionic tube havlng input electrodes and output elec- 

